1. Field of the Invention
The invention relates to an anchor assembly for above ground structures, such as utility towers, communication towers, oil field structures, and the like. More particularly, expandable jaws opening outwardly to engage the soil provide a secure anchor for a rod which serves as the point of attachment for cables, guy wires, or the like conventionally employed in support of above ground structures. The anchor assembly includes a pressure plate for causing outward expansion of the jaws on rotation of the anchor rod from above the surface of the ground. Furthermore, coating of the entire assembly with a fusion-bonded epoxy coating provides protection against electrolytic corrosion and protects against the accelerated rate of corrosion conventionally present in anchor rods which are subject to passage of below ground electrical currents found to be present with buried structures.
2. Description of the Prior Art
The prior art includes earth anchoring devices having expansible blades, for supporting guy wires, posts, telephone poles, and the like. For example, Lewis in U.S. Pat. No. 930,486, patented Aug. 10, 1909, shows an anchor having expanding flukes which pass through and outwardly from the mushroom-shaped crown by rotating a projecting shank independently of the crown. Cole et al. in U.S. Pat. Nos. 1,606,146 and 1,606,147, both issued Nov. 9, 1926, disclose earth anchor devices having anchor blades which can be expanded outwardly by a blade expanding head which engages a locking holder on the blades to lock the blades in their fully extended position, or by an anchor head for use with an associated expander tube with respect to which a rod rotates for frictional engagement with a body portion so as to cause expansion of blades associated therewith. Neither of the Cole et al. patents teaches ribbing on the upper surface of the blades for a locking action.
Bowen in U.S. Pat. No. 1,015,611, patented Jan. 23, 1912, discloses a threaded rod in association with a concavo-convex spreader plate which has its convex surface directed downwardly and which forces the blades, which also have their convex surfaces directed downwardly, in an outward direction. Such an arrangement is not protected from contact with loose soil, a particularly important consideration when mounting an earth anchor at a substantial angle from the vertical. Ogburn in U.S. Pat. No. 2,676,412, patented Nov. 27, 1951, discloses an earth anchor having a plurality of blades which are carried on a follower block and which pass through openings in a spreader block for outward gripping of the earth. Both the Ogburn and Lewis structures, however, are subject to binding where the wings or blades pass through openings during the expansion operation, and any corrosion is likely to render the device inoperable due to seizing of a blade at the opening.
None of the structures of earth anchor assemblies described above includes a ribbed blade surface for expediting locking of the blades in the expanded configuration.
Weatherby, in U.S. Pat. No. 4,124,983, issued Nov. 14, 1978, discloses a corrosion protected earth tieback having a first thin hard coating of corrosion resistant plastic throughout its length and a second coating formed from a heat shrunk plastic tube encapsulating a portion of the rod connecting a grounded anchor to the structure being anchored. The method of protecting the device of Weatherby from corrosion, however, is complex, expensive, and makes specific reference to the unsuitability of epoxy coatings for corrosion protection.
Fusion-bonded epoxy coating products are disclosed in the technical brochure entitled "Product Data-101, 110, and 117 Fusion-Epoxy Coatings," published by 3M Company, Electro-Products Division, St. Paul, Minn. Further technical information is found in a technical publication from the same source entitled "Coating Recommendations--Fusion-Bonded Epoxy Coating Powders, 100, 200, 1,000 Series."